Plant Study 13 



plants produce seeds. However, in farm practice it has been 

 found that some plants can be propagated better commercially 

 by dividing them. (See paragraph 10.) Annual plants such 

 as corn, small grains, and most vegetables are usually propa- 

 gated by seeds. 



In every live seed is the embryo, or germ, which is really a 

 living undeveloped plant. The seed also contains stored-up 

 food material (starch and oil largely) that can be used by the 

 embryo while the seed is sprouting and by the plantlet until it 

 can secure nourishment from the soil and air. When live seeds 

 are placed in a warm, moist, well ventilated soil, they germinate 

 or sprout. They can also be sprouted by placing them between 

 pieces of cloth or blotting-paper and keeping moist and warm. 

 When sprouted seeds are examined, it is seen that the seed- 

 coats have broken and tiny shoots have burst through 

 the opening. The embryo of a seed consists of three parts : 

 the radicle, also known as the caulicle and as the hypocotyl, 

 the part that develops into the root; the plumule, the part 

 that develops into the stem and leaves ; the 

 cotyledons (in some species of plants only 

 one cotyledon is present), the seed leaves 

 that nourish the young plant. A sprouted 

 bean (Fig. 1) may be examined to learn the 

 three parts. The slender stem-like part is FlG l _ A sprouted 

 the radicle, the two tiny leaves between the bean, a, radicle; 

 halves of the bean form the plumule (in the 



illustration the plumule is shown outside the 

 bean), and the halves of the bean are the cotyledons. When 

 a planted bean grows, the cotyledons are brought above the 

 ground and, as the plant continues to develop, they shrink in 

 size, the stored-up food they contain being used by the plant 

 until it obtains sufficient nourishment from the soil. In some 

 cases the stored-up food is separate from the embryo, as in 

 the corn. A corn kernel in cross-section is shown in Fig. 2. 

 The caulicle, plumule, and cotyledon (corn has one cotyle- 



